Borehole profiling and imaging

ABSTRACT

A borehole instrument includes an image sensor for capturing images of an inside wall of a borehole. A borehole profile may also be measured by, for example, a laser. The same image sensor may be used for image capture and profile measurement. Different image sensors may be used for image capture and profile measurement. Image capture and profile measurement may be performed with reference to the same depth measurement, so that images and profiles are depth-aligned at capture. Orientation of the instrument within the borehole may also be measured to compensate for rotation of the instrument. A communications subsystem can transmit image data, profile data, and orientation data to a computer located outside the borehole for storage and analysis.

FIELD

The present invention relates to borehole instruments.

BACKGROUND

Existing borehole instruments are limited in the sense that limitedamounts of data can be captured during a single pass of the instrumentwithin the borehole. Further, such instruments may only be able tocapture data at low rates, which constrains the speed of travel of theinstrument within the borehole and increases the time required tocapture the data.

When an instrument spends much time within the borehole, it cannot beserving other boreholes. Thus, the efficiency of an exploration projectis reduced in waiting for instruments to serve all boreholes. Projectcost and complexity can increase due to an increase in the amount ofinstruments needed. In addition, as the time within a boreholeincreases, the risk of an instrument becoming physically stuck withinthe borehole also increases, and a stuck instrument may have to beabandoned.

Another problem arises in analyzing different sets of data captured bydifferent kinds of borehole instruments. Different sets of data musttypically be aligned with each other by highly skilled people. Forinstance, visual analysis is performed to adjust different datasets sothat they coincide at all depths. The files containing the datasets arethen typically merged. This can lead to errors and additional timebefore data is ready for geological analysis.

Furthermore, because running different instruments in the same boreholeadds time to a project, datasets considered nice-to-have but notessential to a project are often missing because time saving wasparamount and an optional instrument was not run.

Thus, state-of-the-art borehole instruments may cause explorationprojects to be carried out with poor efficiency, and further may resultin gaps in geological knowledge.

SUMMARY

According to one aspect of the present invention, a borehole instrumentincludes a housing sized and shaped to fit inside a borehole and anoptical imager disposed within the housing. The optical imager has animage sensor configured to capture images of an inside wall of theborehole. The borehole instrument further includes a borehole profilerdisposed within the housing and configured to emit a signal towards theinside wall of the borehole to measure a profile of the inside of theborehole. The borehole instrument further includes a communicationssubsystem coupled to the optical imager and to the borehole profiler.The communications subsystem is configured to receive image data fromthe optical imager and to receive profile data from one of the opticalimager and the borehole profiler. The communications subsystem isfurther configured to transmit the image data and the profile data alongat least one transmission line to outside of the borehole.

The borehole profiler can include a laser.

The image sensor can be further configured to capture profilemeasurements as laser light reflected by the inside wall of theborehole. The communications subsystem can be further configured toreceive profile data from the optical imager.

The optical imager can include a light source positioned to illuminatethe inside wall of the borehole.

The housing can include a window aligned with the image sensor, thelight source, and the laser.

The borehole profiler can further include another image sensorconfigured to capture profile measurements as laser light reflected bythe inside wall of the borehole. The communications subsystem can befurther configured to receive profile data from the borehole profiler.

The instrument can further include a direction sensor configured todetermine an orientation of the borehole instrument within the borehole.The direction sensor can be coupled to the communications subsystem. Thecommunications subsystem can further be configured to receiveorientation data from the direction sensor and transmit the orientationdata along the transmission line to the outside of the borehole.

According to another aspect of the present invention, a method ofcapturing data from a borehole includes capturing images of an insidewall of the borehole, measuring profiles of the inside of the borehole,transmitting captured image data and captured profile data to a computeroutside the borehole, and performing the capturing, measuring, andtransmitting during a same pass through the borehole.

The capturing and measuring can be performed based on a same depthmeasurement of the same pass within the borehole to generatedepth-aligned datasets of image data and profile data.

The method can further include capturing orientations of a sensor withinthe borehole during the same pass.

The method can further include measuring the profiles using a laser.

The capturing and measuring can be performed using a same image sensor.

The capturing and measuring can be performed using different imagesensors.

According to another aspect of the present invention, a boreholeinstrument includes a housing sized and shaped to fit inside a borehole.The housing has a window. The instrument further includes a light sourcedisposed within the housing and aligned with the window. The lightsource is configured to illuminate an inside wall of the borehole. Theinstrument further includes a laser disposed within the housing andaligned with the window. The laser is configured to emit laser lighttowards the inside wall of the borehole. The instrument further includesan image sensor disposed within the housing and aligned with the window.The image sensor is configured to capture light of the light sourcereflected by the inside wall of the borehole to capture images of theinside wall of the borehole. The image sensor is further configured tocapture laser light reflected by the inside wall of the borehole tomeasure the profile of the borehole. The instrument further includes acommunications subsystem coupled to the image sensor. The communicationssubsystem is configured to receive image data and profile data from theimage sensor. The communications subsystem is further configured totransmit the image data and the profile data along at least onetransmission line to a computer outside the borehole.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of borehole analysis using a boreholeinstrument according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of the borehole instrument.

FIG. 3 is a functional block diagram of the borehole instrument.

FIG. 4 is a functional block diagram of a borehole instrument accordingto another embodiment.

DETAILED DESCRIPTION

The present invention relates to an in-situ borehole instrumentconfigured to capture several different datasets from a borehole in asfew passes as possible and as fast as possible, and at higherresolution. In some embodiments and under certain dataset requirementsand borehole conditions, only a single pass of the borehole instrumentis needed. Because different datasets can be captured during the samepass, the need to align different datasets at a later time is reduced oreliminated. Many of the problems discussed above are solved or havetheir detrimental effects reduced.

The present description adopts the context of geological analysis in thefield of mining and mineral exploration. However, the boreholeinstruments, methods, and other techniques described herein may findother uses and solve problems in other fields, such as pipe inspection,oil and gas exploration and scientific study.

FIG. 1 shows a borehole instrument 10 being used to collect data from aborehole 12 drilled into a rock formation 14. The instrument 10 may beknown as a borehole televiewer. The borehole 12 may be open or cased.The borehole instrument 10 is connected to the surface by a cable 16that runs from the borehole instrument 10 to outside the borehole 12,through a rigging apparatus 18, and to a vehicle 20.

The cable 16 physically carries the weight of borehole instrument 10, aswell as its own weight, as the borehole instrument 10 is raised andlowered within the borehole 12. To assist in this, the rigging apparatus18 may include a pulley supported by one or more support arms, which mayextend from the vehicle 20 or may be braced against the ground. At thevehicle 20, the cable 16 can be wrapped around a drum or winch that isdriven to spool the cable 16 in and out.

The cable 16 can also connect the borehole instrument 10 to the vehicle20 for the purposes of signal communications. The cable 16 may thereforeinclude one or more wire conductors, which may be situated within aweight-carrying braided steel sheath. The vehicle 20 can include dataacquisition hardware, such as a computer 22 or other device that isconnected to the wire conductors inside the cable 16.

The vehicle 20 can be a truck, van, or similar. In other embodiments, anon-vehicular winch is provided mounted to a portable frame, which canbe configured to be air-dropped to remote regions.

A depth transducer 24, such an optically encoded wheel in frictionalcontact with the cable 16, is connected to the computer 22 to measurethe depth of the borehole instrument 10 in the borehole 12 (i.e., withrespect to the surface of the ground or some other reference datum).Depth data 30 can therefore be collected based on the spooling andunspooling of the cable 16. The depth data 30 can be compensated forcable stretch and other factors so that an accurate depth of theborehole instrument 10 can be recorded. The depth data 30 can berecorded in any increment (e.g., 1 mm, 1 cm, 2 cm, etc.). The depthtransducer may be capable of determining depth with a higher degree ofprecision. For illustrative purposes, it is assumed that N samples ofdepth data 30 are taken for a particular borehole, so that depths D(1),D(2) . . . D(N) are measured and stored at the computer 22.

The borehole instrument 10 is configured to capture image data 32 ofimages of the inside wall of the borehole 12. In this embodiment, imagesI(1), I(3) . . . I(N-2), I(N) are captured at regular depths D(1), D(3). . . D(N-2), D(N) and transmitted to outside the borehole 12 via thecable 16 to be stored in the computer 22. The images captured have aheight (e.g., 2-4 cm), so that images need not be captured at each depthincrement and so that sufficient overlap exists to splice imagestogether. For example, image I(1) is captured at depth D(1), image I(3)is captured at depth D(3), and the height of the captured images meansthat no image need be captured at depth D(2) and that images I(1) andI(3) have sufficient overlap to provide an image at depth D(2) and topermit splicing of images I(1) and I(3) to produce a continuous image ofa segment of the borehole 12.

The borehole instrument 10 is also configured to measure the profile ofthe inside wall of the borehole 12 to capture profile data 34. Boreholeprofiles define the interior dimensions of the borehole and can includea series of radial measurements, a series of diametrical measurements, aseries of deviations (+/−) from nominal diameter or radius, or the like.In this embodiment, borehole profiles P(1), P(2) . . . P(N) are measuredat regular depths D(1), D(2) . . . D(N) and transmitted to outside theborehole 12 via the cable 16 to be stored in the computer 22.

The borehole instrument 10 is also configured to measure its directionor orientation within the borehole 12 to capture orientation data 36.Direction data may be measured and stored with respect to a referencedatum, such as magnetic north. In this embodiment, instrumentorientations S(1), S(2) . . . S(N) are measured at regular depths D(1),D(2) . . . D(N) and transmitted to outside the borehole 12 via the cable16 to be stored in the computer 22. The orientation data 36 can be usedto laterally shift captured images and profile measurements tocompensate for any rotation of the borehole instrument 10 within theborehole 12.

The borehole instrument 10 performs image capture, profile measurement,and orientation measurement during the same pass of the borehole 12.Captured image data 32 and profile data 34 are thus both measureddirectly in association with the same depth and orientationmeasurements. This means that images and profile measurements aredepth-aligned and of the same orientation without the need for postprocessing, which has until now included substantial human effort.

FIG. 2 shows the borehole instrument 10 in greater detail. The boreholeinstrument 10 includes a housing 42 sized and shaped to fit inside theborehole 12 with clearance. In this embodiment, the housing 42 includesa hollow metal cylindrical tube having closed ends. A transparent orsemi-transparent window 44 is provided in the housing 42 and ispositioned to allow light emitted from inside the housing 42 toilluminate the inside wall of the borehole 12. In this embodiment, thewindow 44 includes a hollow transparent cylinder made of glass orsimilar material. The window 44 can be made of abrasion-resistantmaterial and can have an outside diameter smaller than the outsidediameter of the housing 42 to reduce wear induced by the borehole 12.

The borehole instrument 10 may further include one or more centralizers45 attached to the outside of the housing 42. The centralizers 45 serveto keep the borehole instrument 10 centered in the borehole 12. When onecentralizer 45 is used, it may be located above or below the window 44.When two or more centralizers 45 are used, there may be centralizers 45located above and below the window 44.

The borehole instrument 10 further includes an optical imager 52, aborehole profiler 54, a direction sensor 58, and a communicationssubsystem 56 disposed within the interior 46 of the housing 42. Theoptical imager 52, borehole profiler 54, and direction sensor 58 areeach electrically connected to the communications subsystem 56, which isconnected to the computer 22 via one or more conductive transmissionlines 62, which form part of the cable 16.

The cable 16 further includes an electrically insulative inner sheath 64that electrically isolates the conductive transmission lines 62 from anouter braided cable sheath 66, which can be made of steel braid andprovides tensile strength to the cable 16.

Light and other signals emitted from and captured by one or more of theoptical imager 52 and the borehole profiler 54 pass through the window44. Data captured about the borehole 12 using the optical imager 52,borehole profiler 54, and direction sensor 58 are collected by thecommunications subsystem 56 synchronously, so that image data 32,profile data 34, and orientation data 36 are inherently depth aligned atcapture. Power can be provided to the components 52-58 along one or moreof the lines 62, and the outer sheath 66 may be used to providegrounding.

FIG. 3 shows a functional block diagram of the borehole instrument 10.

The optical imager 52 includes a light source 72 positioned toilluminate an inside wall 82 of the borehole 12 via the window 44. Theoptical imager 52 further includes an image sensor 74 aligned with thewindow 44 and positioned to capture images of the inside wall 82 of theborehole 12. The optical imager 52 may further include a processor,memory, and other hardware to perform image capture. Imaging lightemitted and reflected by the optical imager 52 is shown as dashed lines.

The borehole profiler 54 is configured to emit a signal towards theinside wall 82 of the borehole 12 to measure the profile of the insideof the borehole 12. In this embodiment, the borehole profiler 54includes a laser 76 aligned with the window 44. Laser light emitted bythe laser 76 and reflected from the wall 82 is shown in dotted line. Thelaser 76 is aligned so that laser light reflected by the inside wall 82of the borehole 12 is incident upon the image sensor 74 of the opticalimager 52, which captures profile measurement signals of the inside wall82 of the borehole 12 in the form of images of reflected laser light.One advantage of using the laser 76 is that profiles can be measured inwet, dry, or partially dry boreholes.

The image sensor 74 may be a high-speed and high-resolutioncharge-coupled device (CCD) or CMOS image sensor, or similar. In thisembodiment, the light source 72 and image sensor 74 are configured tocapture full-color images in, for instance, the RBG color-space. A setof optics may be provided to direct and focus both the light of imagesto be captured and laser light from the profiler 54 into the imagesensor 74.

The light source 72, image sensor 74, and laser 76 are configured tocapture data for the full 360 degrees of the inside of borehole 12.

In this embodiment, the same image sensor 74 is used to capture imagedata 32 and profile data 34. Using a single image sensor canadvantageously reduce the weight, size, and cost of the boreholeinstrument 10. Further, this may also reduce the complexity of thecommunications subsystem 56, in that the communications subsystem 56 mayonly be required to transmit one format of data, i.e., data captured bythe image sensor 74.

The direction sensor 58 may be a magnetometer with tilt-meters, agyroscope, an inertial sensor, or similar device configured to generateorientation signals with reference to magnetic north or to the high sideof the borehole in angled holes.

As shown, the communications subsystem 56 is electrically coupled to theoptical imager 52, the borehole profiler 54, and the direction sensor 58to receive images, profile measurement signals, and orientation signalsfrom the optical imager 54, which carries the shared image sensor 74.The communications subsystem 56 may communicate power level settings forthe light source 72 and the laser 76, and may further communicatecapture signals indicative of when to capture images and profilemeasurements. Capture signals may include depth data 30, which is thenencoded with the image data 32, profile data 34, and orientation data 36before such is sent up-hole along the lines 62 to the computer 22.

The communications subsystem 56 may use any suitable protocol fortransmitting the captured data 32-36 along the lines 62, and suchprotocol may depend on the length of the cable 16, the speed of theborehole instrument, and the amount of data 32-36 to be captured, amongother factors. In this embodiment, the protocol is configured totransmit image data for 360-degree full-color images with 0.5 mmresolution and profile data also at 0.5 mm resolution at speeds of 6m/min of the instrument 10 within the borehole 12 under normal operatingconditions. The protocol may employ data compression and errorcorrection.

FIG. 4 shows a functional block diagram of a borehole instrument 90according to another embodiment, in which two image sensors are used.The instrument 90 is similar to the instrument 10 and for clarity, andonly differences will be described in detail. For other features andaspects of the instrument 90, the description of the instrument 10 canbe referenced, with like reference numerals identifying like elements.

The borehole instrument 90 includes a borehole profiler 94 similar tothe borehole profiler 54. The borehole profiler 94 includes an imagesensor 96 positioned to capture laser light emitted by the laser 76 andreflected from the inside wall 82 of the borehole 12. The image sensor96 thus measures the borehole profile, while the different image sensor74 of the optical imager 82 can be dedicated to capturing images of theborehole wall 82.

The image sensor 96 may be a high-speed and high-resolution CCD or CMOSimage sensor, or similar. In this embodiment, the image sensor 96 isconfigured to capture light of the wavelength band of the laser 76.

The image sensors 74, 96 may be of the same or different types. Theimage sensors 74 and 96 may have different sets of optics.

With reference to FIGS. 3 and 4, in other embodiments, the boreholeprofiler 54 is an acoustic device that includes a rotating transducerthat transmits an acoustic pulse into the borehole 12 and measures thereturning amplitude and travel time of the pulse reflected from theborehole wall 82. Profile data 34 is thus captured by the rotatingtransducer. This embodiment is suitable for use in wet boreholes andwhen moving parts can be tolerated.

In view of the above, it should be apparent that the present inventionallows data capture to be performed faster. For example, up until now a1000 meter borehole may have required as much as 800 minutes of scanningtime (i.e., 400 minutes each for a profile pass and a separate imagingpass). With the present invention, a single pass of 400 minutes capturesdepth-aligned and mutually oriented profile data and image data,resulting in substantial time saved. Moreover, increased data capturespeed allows for faster movement in the borehole, such that totalcapture time may be reduced to less than 200 minutes.

Further, there can be a reduction in the amount of manual work andpotential for error in manually aligning profile data and image data.This may also further save time.

In addition, image and profile data can be acquired with higherresolution than currently available. For example, existing acousticprofile technology is limited by a 2 mm acoustic beam diameter, whichmeans that the typical highest resolution possible is a 2 mm×2 mm pixelsize or a maximum annular resolution of 288 measurements per 360degrees. A 2 mm pixel size is usually not adequate to measure roughnessin situ. When using the laser as discussed herein, pixel size can be assmall as 0.5 mm×0.5 mm, which can result in an annular resolution ofapproximately 1000 measurements per 360 degrees.

In addition, it is advantageous that use of the laser for profilemeasurements allows such measurements to be taken in wet, dry, andpartially dry boreholes.

While the foregoing provides certain non-limiting example embodiments,it should be understood that combinations, subsets, and variations ofthe foregoing are contemplated. The monopoly sought is defined by theclaims.

What is claimed is:
 1. A borehole instrument comprising: a housing sizedand shaped to fit inside a borehole; an optical imager disposed withinthe housing, the optical imager having an image sensor configured tocapture images of an inside wall of the borehole; a borehole profilerdisposed within the housing and configured to emit a signal towards theinside wall of the borehole to measure a profile of the inside of theborehole; and a communications subsystem coupled to the optical imagerand to the borehole profiler, the communications subsystem configured toreceive image data from the optical imager and to receive profile datafrom one of the optical imager and the borehole profiler, thecommunications subsystem further configured to transmit the image dataand the profile data along at least one transmission line to outside ofthe borehole.
 2. The instrument of claim 1, wherein the boreholeprofiler comprises a laser.
 3. The instrument of claim 2, wherein theimage sensor is further configured to capture profile measurements aslaser light reflected by the inside wall of the borehole, and thecommunications subsystem is configured to receive profile data from theoptical imager.
 4. The instrument of claim 2, wherein the optical imagercomprises a light source positioned to illuminate the inside wall of theborehole.
 5. The instrument of claim 4, wherein the housing comprises awindow aligned with the image sensor, the light source, and the laser.6. The instrument of claim 1, wherein the borehole profiler furthercomprises another image sensor configured to capture profilemeasurements as laser light reflected by the inside wall of theborehole, and the communications subsystem is configured to receiveprofile data from the borehole profiler.
 7. The instrument of claim 1,further comprising a direction sensor configured to determine anorientation of the borehole instrument within the borehole, thedirection sensor coupled to the communications subsystem, and thecommunications subsystem further configured to receive orientation datafrom the direction sensor and transmit the orientation data along thetransmission line to the outside of the borehole.
 8. A method ofcapturing data from a borehole, the method comprising: capturing imagesof an inside wall of the borehole; measuring profiles of the inside ofthe borehole; transmitting captured image data and captured profile datato a computer outside the borehole; and performing the capturing,measuring, and transmitting during a same pass through the borehole. 9.The method of claim 8, wherein the capturing and measuring are performedbased on a same depth measurement of the same pass within the boreholeto generate depth-aligned datasets of image data and profile data. 10.The method of claim 8, further comprising capturing orientations of asensor within the borehole during the same pass.
 11. The method of claim8, further comprising measuring the profiles using a laser.
 12. Themethod of claim 11, wherein the capturing and measuring are performedusing a same image sensor.
 13. The method of claim 11, wherein thecapturing and measuring are performed using different image sensors. 14.A borehole instrument comprising: a housing sized and shaped to fitinside a borehole, the housing having a window; a light source disposedwithin the housing and aligned with the window, the light sourceconfigured to illuminate an inside wall of the borehole; a laserdisposed within the housing and aligned with the window, the laserconfigured to emit laser light towards the inside wall of the borehole;an image sensor disposed within the housing and aligned with the window,the image sensor configured to capture light of the light sourcereflected by the inside wall of the borehole to capture images of theinside wall of the borehole, the image sensor further configured tocapture laser light reflected by the inside wall of the borehole tomeasure the profile of the borehole; and a communications subsystemcoupled to the image sensor, the communications subsystem configured toreceive image data and profile data from the image sensor, thecommunications subsystem further configured to transmit the image dataand the profile data along at least one transmission line to a computeroutside the borehole.
 15. The instrument of claim 14, further comprisinga direction sensor configured to determine an orientation of theborehole instrument within the borehole, the direction sensor coupled tothe communications subsystem, and the communications subsystem furtherconfigured to receive orientation data from the direction sensor andtransmit the orientation data along the transmission line to thecomputer outside of the borehole.